A conventional domestic fan typically includes a set of blades or vanes mounted for rotation about an axis, and drive apparatus for rotating the set of blades to generate an air flow. The movement and circulation of the air flow creates a ‘wind chill’ or breeze and, as a result, the user experiences a cooling effect as heat is dissipated through convection and evaporation. The blades are generally located within a cage which allows an air flow to pass through the housing while preventing users from coming into contact with the rotating blades during use of the fan.
The use of fans in hospitals to keep patients cool is widespread, both in general wards and in isolation wards. For example, depending on the medical condition of the patient it may be preferable to reduce the body temperature of the patient using a fan rather than by using pharmaceuticals. When a fan is assigned to a patient, generally that fan is treated as an item of medical equipment and so, like other medical equipment, will require frequent cleaning by a nurse or other hospital employee. The cleaning of bladed fans can be time consuming for the employee, as the cage housing the blades of the fan needs to be disassembled before the blades of the fan can be cleaned. This disassembly usually requires the use of a screw driver, which cannot be carried by a nurse on a hospital ward. Often, it can be more convenient for the hospital to engage a specialist cleaning company to clean the fan off site, although this can be very expensive.
WO 2009/030879 describes a fan assembly which does not use caged blades to project air from the fan assembly. Instead, the fan assembly comprises a base which houses a motor-driven impeller for drawing a primary air flow into the base, and an annular nozzle connected to the base and comprising an annular slot through which the primary air flow is emitted from the fan. The nozzle defines a central opening through which air in the local environment of the fan assembly is drawn by the primary air flow emitted from the mouth, amplifying the primary air flow.
The time required to clean off the external surfaces of this type of “bladeless” fan is much shorter than that required to clean a fan having caged blades, as there is no requirement to dismantle any parts of the fan to access any exposed parts of the fan. For example, the external surfaces of the fan may be wiped clean using a cloth. While this level of cleaning may be sufficient for bladeless fans which are assigned to patients on general wards, when the bladeless fan is assigned to a patient in an isolation ward or infection containment ward there remains a need to keep the internal components of the base clean to avoid cross-contamination when the fan is assigned to another patient.